Wide Area Voltage stability assessment based on generator derived indices using phasor measurement units

Abstract

The continuous increase in energy demand without a concomitant increase in generation and transmission capabilities inevitably leads to power system instability and consequently blackouts. This paper proposes and investigates the application of generator-derived Voltage Stability (VS) indices using synchrophasor measurements from dispersed Phasor Measurement Units (PMUs) for real-time monitoring and situational awareness in power systems. Three VS indices derived from the capability parameters of synchronous generators in the power system are presented, and used in the prediction of the power system's margin to voltage collapse. The proposed generator-derived VS indices were tested using the New England 39-bus benchmark test system modelled using RSCAD software. Real-time hardware-in-the-loop simulations involving a lab-scale testbed using the Real-Time Digital Simulator (RTDS), PMUs, Phasor Data Concentrators (PDCs), Programmable Logic Controller (PLC), communication network switches, and GPS satellite clock were carried out in order to test the proposed VS indices for various system operating conditions encompassing credible contingencies, increased system loading, operation of transformer Under-Load TapChangers (ULTCs), and generator Over Excitation Limiters (OXLs). The results obtained showed that the VS indices provided an exact snap-shot of the grid in real-time. The VS indices would be useful in the design of System Integrity Protection Schemes (SIPS) that are capable of preserving the integrity of the grid during disturbances and parametric changes, thereby preventing system blackouts.